This invention relates to high-quality surveillance camera systems capable of capturing information from a scene under light conditions ranging from dark to well-lit.
The invention provides a camera system that switches electronically between infrared radiation sensing and visible light sensing depending on ambient conditions. The camera is provided with a bandpass filter having a stop band between the infrared radiation spectrum and the visible light spectrum in order to provide high quality visible light images when not in the infrared mode and high quality mono infrared images when not in visible light mode. The bandpass filter assists in quantifying the ambient light for the switching control circuit.
The purpose of the system is to provide 24 hour CCTV viewing capability of a scene irrespective of ambient lighting conditions. This is achieved by analyzing and quantifying the ambient light available. The system then chooses the appropriate mode of operation to produce optimized picture quality.
The system comprises of the following components each of which will be further detailed below:
a) An electronic colour video CCD camera;
b) A specially designed optical bandpass filter to be used in the camera;
c) An infrared illuminator;
d) A photocell with an optical filter having a specific optical response;
e) an electronic control circuit.
The electronic control circuit integrates the functions of the component parts and enables the camera system that to switch electronically between infrared radiation sensing and visible light sensing depending on ambient conditions.